Fix several harmless compiler warnings.  Fix a couple compiler issues with the shell.
Remove hard-coding of the directory separator in the Win32 VFS.  Fixes to OSTRACE macros.
Make names of private functions in the Win32 VFS consistent.  Fix comment typo in Win32 mutex implementation.
Support database file names longer than 260 characters using the new 'win32-longpath' VFS variant.
In the win32longpath test, move the journal mode change down where it was intended to be.